1. Field of the Invention
The present invention relates to a tire vulcanizing method for vulcanizing a tire by heating and pressurizing the tire, and a tire vulcanizer.
2. Description of the Related Art
For example, Japanese Unexamined Patent Application Publication No. H4-14413 describes a conventional tire vulcanizing method and a conventional tire vulcanizer. The tire vulcanizer includes a mold, a bladder provided in the vulcanizer, and piping for supplying a heating and pressurization medium to an internal space of the bladder and the like. In this tire vulcanizer, an unvulcanized green tire (hereinafter, simply referred to as the “tire”) is brought into the mold, the bladder is fitted along an inner surface of the tire, and the heating and pressurization medium is introduced to an interior of the bladder. The mold and the bladder heat and pressurize the tire. Thereby, a vulcanization reaction is progressed in the tire. By this tire vulcanizing method, a tread pattern of the tire is formed. In this tire vulcanizing method, the heating and pressurization medium supplied to the internal space of the bladder is steam and an inert gas (nitrogen gas).
In a tire vulcanizing method described in US Patent Application Publication No. 2010/0007038, a heating and pressurization medium is only an inert gas. A tire vulcanizer of this (refer to FIG. 1 of the above publication) includes a circulation device (6) for circulating the inert gas, and a heating device (8) for heating the inert gas.
In a technique described in Japanese Unexamined Patent Application Publication No. H4-14413, steam is used as the heating and pressurization medium. Therefore, this technique holds a problem that a temperature difference is generated between upper and lower parts of the tire by a drain (problem 1), a problem that productivity of the tire vulcanization is lowered by re-evaporation of the drain (problem 2), and a problem that an energy consumption amount is large due to difficulty in re-use of energy (problem 3).
In a technique described in US Patent Application Publication No. 2010/0007038, energy is to be saved more (problem 4). As described above, the tire vulcanizer described in the same publication includes the circulation device for circulating the inert gas. At the time of heating and pressurizing the tire, this circulation device is always rotated. Therefore, in this technique, the energy may be saved more.
It should be noted that the same publication also describes that the circulation device may be stopped after a fixed time elapses from start of heating and pressurization of the tire ([0074] in the same publication). However, when the circulation device is stopped, a temperature of the entire tire vulcanizer is decreased by radiation of heat. As a result, it is thought that an initial temperature of bladder at a time point when vulcanization of next cycle is started is decreased, and a temperature increase of the tire is delayed. The same publication does not describe a timing for stopping the circulation device.